Method of rebuilding an evacuated electron tube

ABSTRACT

A method of rebuilding a cathode ray tube, including the penetration of a metallic part of the tube by means of a pointed tool, for example. Defective parts of the vented tube can be replaced or the re-usable parts thereof can be reclaimed. The opening in the metallic part of the tube can be hermetically sealed with a frit material or by sealing to the metallic part a pin that is inserted in the opening therein.

United States Patent Haines 1 May 16, 1972 [54] METHOD OF REBUILDING AN 3,063,777 11/1962 Trax ..3l6/2 EVACUATED ELECTRON TUBE 3,404,933 10/1968 Weideman ..3l6/2 [72] Inventor: Alan Paul flames, Lancaster, Pa. Primary Examiner john R Campbell [73] Assignee: RCA Corporation Assistant Examiner-Richard Bernard Lazarus [22] Filed Apr 30 1970 Attorney-Glenn H. Bruestle [21] Appl. No.: 33,388 [57] ABSTRACT A method of rebuilding a cathode ray tube, including the U-S. l a .-.316/2 penetration of a metallic part of the tube means of a [51] ll lt. Cl ..H0lj 9/50 pointed too], for example Defective pans f the vented tube [58] Field oiSearch ..3l6/1, 2; 313/64; 53/43 can be replaced or the remsable parts thereof can be reclaimed. The opening in the metallic part of the tube can be [56] References cued hermetically sealed with a frit material or by sealing to the UNITED STATES PATENTS v metallic part a pin that is inserted in the opening therein. 2,820,166 I/ l 958 Pinotti ..3 13/64 4 Claims, 4 Drawing Figures BACKGROUND OF THE INVENTION This invention relates to themanufacture of electron tubes and particularly to a novel method of rebuilding cathode ray tubes wherein an internal defective part or assembly is replaced with an operative part or assembly.

Cathode ray tubes of the type generally employed in television receivers comprise an envelope including neck, funnel, and faceplate portions. A phosphor screen is disposed on the internal surface of the faceplate portion and an electron gun is positioned in the neck portion to project at least one electron beam toward and upon the phosphor screen. In the manufacture of such cathode ray tubes, a defective electron gun is occasionally incorporated into what is otherwise a good tube. Also, the electron gun of a normally good tube may become defective after a normal life span of tube operation. In either case, the phosphor screen and envelope of the tube may be suitable for further use. Accordingly, it has been the practice to rebuild such cathode ray tubes by replacing the defective gun with a new gun.

Generally, the prior art practice for rebuilding of such defective cathode ray tubes comprises first opening the envelope of the tube to admit air and thus equalize the pressures on the inside and outside of the tube envelope. A section of the neck is then cracked off and the old electron gun removed. A new neck section is then spliced onto the tube to provide a complete envelope. The remainder of the rebuilding process then follows the usual manufacturing steps used in completing a new tube.

Numerous approaches have been takenin the cathode ray tube prior art for admitting air or other gases to the tube interior. Generally, these approaches involve puncturing the neck portion of the glass envelope by means of a heated metallic tip to melt a hole in the glass or by means of a rapidly revolving drill; marking the neck portion of the tube with a glass cutter and then heating the marked, or scratched, portion to crack the neck; or breaking off the sealed glass evacuation tubulation of the envelope. Such means for admitting air are not completely satisfactory due to the possibility that glass particles, in the form of chips, molten glass; or melted and resolidified glass, will be carried to the interior by the air that is allowed to. rush into the envelope when the tube is first opened. Such particles can cause blocking of the apertures of an electrode in the tube (tag, the shadow mask), damage to the phosphor screen, or other undesirable results.

SUMMARY OF THE INVENTION The invention is a novel method of rebuilding an evacuated electron tube (including reclaiming re-usable parts thereof) that includes an envelope and a metallic member in the wall of the envelope. The method comprises penetrating the metallic member and admitting a gas to the interior of the electron tube via the opening provided in the metallic member. The penetration of the metallic member can be done by means of a manuallyor mechanicallydriven pointed tool.

Where the tube that is so vented is a cathode ray tube, it can be rebuilt so as to replace a defective electron gun by removing a part of the neck member of the envelope of the tube and the defectivqelectron gun; providing a new neck segment and a new electron gun to the envelope; hermetically sealing the opening in the metallic member; and evacuating the tube. The opening in the metallic member, which can be the high voltage connection of a kinescope tube, can be hermetically sealed by, inter alia, plugging the opening with a frit material, or inserting a pin in the opening and sealing the pin to the metallic member with a frit material or by welding.

The present invention provides the advantage of eliminating the possibility of glass or other particles being introduced into the tube by the venting operation.

FIG. 1 is an elevation view, partially cut-away in section, of a color kinescope. which is one type of device on which the present invention can be practiced; the kinescope including a metallic high voltage button in the envelope thereof.

FIG. 2 is a fragmentary sectional view, along the line 2-2 of the high voltage button and the envelope in FIG. 1, the button being shown before the tool that is shown.

, FIG. 3 is a similar view of the envelope and high voltage button after the button has been penetrated to provide the opening therein.

FIG. 4 is a similar view of the envelope and the high voltage button during the subsequent process of hermetically sealing the opening in the button, there being a pin inserted in the opening.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, an evacuated electron tube, such as a cathode ray tube 10, for example, includes an envelope 12 comprising a neck member 13, a funnel member 14 and a cover, or panel, member 16, that includes a faceplate portion 18, that are penetration thereof by the pointed joined in a well-known manner. The neck member 13 contains at least one electron gun (not shown); a color. selection barrier, or shadow mask, 30 including a multiplicity of apertures 32 therein; and discrete deposits 34 of phosphor material on the interior surface 36 of the faceplate portion 18 where, as in this case, the cathode ray tube 10 is a color kinescope. The phosphor deposits 34 are usually covered with an electronpermeable, electrically conducting layer 37 (e.g., aluminum),

7 as is known in the art. The cathode ray tube 10 includes an electrically conductive coating 38 at the interior surface 40 thereof and a high voltage (or ultor potential) connection terminal 42 that is embedded in the wall of the envelope 12. The conductive coating 38 is electrically connected to the conducting layer 37 and to the connection terminal 42, the latter serving to electrically link the conductive coating 38 and the conducting layer 37 to external voltage sources.

Where the evacuated tube (e.g., 10) contains a defective electron gun or other defective replaceable part, air or some other gas can be admitted into the tube and, thereafter, the defective part replaced and the tube again evacuated, thereby rebuilding a previously unsatisfactory tube. The method of rebuilding a tube is generally known in the art (cf. US. Pat. No. 3,063,077 to A.M. Trax). As used herein, the term rebuilding includes both the replacement of some defective part of a tube, and the removal of a re-usable part of a defective tube and subsequent use thereof.

To admit air or another gas to the evacuated tube 10, the high voltage terminal 42 is penetrated with a pointed tool 50 (FIG. 2) that is driven into the terminal 42 manually or by means of a mechanical drive apparatus, for example. Because it is usually made of a relatively ductile material (e.g., Sylvania No. 4 containing 42% nickel, 6% chrome, and 52% iron), the terminal 42 can be deformed with no chipping or other breakage of parts therefrom so that no chips, etc., are introduced into the tube 10. Thus, undesirable results, such as the blocking of the apertures 32 in the mask 30 can be avoided.

The tool 50 can be removed from the terminal 42 upon the puncturing of the latter so that the opening 44 (FIG. 3) provided in the terminal 42 is unobstructed and air or another gas can pass to the interior of the tube 10. Alternatively, the tool can be removed from the opening 44 in the terminal 42 some time after the puncturing of the terminal 42, so that air or gas is introduced more slowly into the tube 10 via the relatively small space between the tool 50 and the adjacent parts of the terminal 42.

Where a defective electron gun is to be replaced, a section of the neck member 13 of the envelope of the vented tube 10 is cracked off with a hot wire ring, for example, according to known procedure. The cracked-off neck section is then removed, taking therewith the defective electron gun. Subsequently, a new neck section is spliced to the end of the remaining part of the neck member, the splicing operation being performed conventionally with glass burners to soften the adjacent ends of the new neck section and the old neck member or by other means known in the art. One or more electron gun assemblies are then sealed into the neck member by softening (e.g., by means of a gas flame) the neck member adjacent to the stem. The tube is subsequently re-evacuated and sealed-off according to known procedures.

The opening 44 provided in the terminal 42 is hermetically sealed at some point in the processing before the final evacuation of the tube. This can be done, for example, by plugging the opening with a frit material or by inserting a pin 56 in the opening 44 and then sealing the pin 56 to the terminal 42 by, for example, a frit material or by welding.

I claim:

1. In a method of rebuilding a cathode ray tube including an evacuated envelope having a metallic member in the wall thereof comprising the steps of:

a. penetrating the metallic member with a pointed tool to form an opening therein b. removing said tool to unobstruct said opening,

0. admitting a gas to the interior of said envelope through said opening,

d. rebuilding said tube,

e. and sealing said opening in said metallic member.

2. The method defined in claim 1, wherein said metallic member comprises an external connection terminal for an electrode of said cathode ray tube.

3. The method defined in claim 2 wherein said electron tube is a kinescope and said external connection is a metal anodecontact thereof.

4. A method for repairing a cathode-ray tube having a defective electron gun contained within an evacuated envelope, said envelope including a neck member and a metallic member extending through the wall thereof, said method comprising:

a. penetrating said metallic member with a pointed metallic tool to form an opening therein;

b. admitting a gas to the interior of said cathode ray tube through said opening so as to substantially equalize the pressure within said envelope and without said envelope;

c. removing at least a part of said neck member and the defective electron gun from said envelope;

d. providing a new neck segment and a new electron gun to said neck portion;

e. hermetically sealing said opening in said metallic member; and

f. evacuating said envelope.

* III k k 

1. In a method of rebuilding a cathode ray tube including an evacuated envelope having a metallic member in the wall thereof comprising the steps of: a. penetrating the metallic member with a pointed tool to form an opening therein b. removing said tool to unobstruct said opening, c. admitting a gas to the interior of said envelope through said opening, d. rebuilding said tube, e. and sealing said opening in said metallic member.
 2. The method defined in claim 1, wherein said metallic member comprises an external connection terminal for an electrode of said cathode ray tube.
 3. The method defined in claim 2 wherein said electron tube is a kinescope and said external connection is a metal anode-contact thereof.
 4. A method for repairing a cathode-ray tube having a defective electron gun contained within an evacuated envelope, said envelope including a neck member and a metallic member extending through the wall thereof, said method comprising: a. penetrating said metallic member with a pointed metallic tool to form an opening therein; b. admitting a gas to the interior of said cathode ray tube through said opening so as to substantially equalize the pressure within said envelope and without said envelope; c. removing at least a part of said neck member and the defective electron gun from said envelope; d. providing a new neck segment and a new electron gun to said neck portion; e. hermetically sealing said opening in said metallic member; and f. evacuating said envelope. 